| Larkshall Contracts Limited | Construction | 2023 |
| Latchingdon Road SPV Ltd | Real estate | 2024 |
| Lazarus Training Ltd | Education | 2011 |
| Lazy Duck Studios Ltd | Wholesale & retail | 2018 |
| LDK Furnishings Ltd | Other services | 2024 |
| Leah Rose Hair and Beauty Ltd | Other services | 2018 |
| LEE Upton Coaching Ltd | Arts & recreation | 2026 |
| Legal & Trustee Probate Services Limited | Administrative & support | 1997 |
| Leisure Innovations Limited | Arts & recreation | 1992 |
| Leo's Locker Ltd | Wholesale & retail | 2024 |
| Lesmek Ltd | Wholesale & retail | 2025 |
| LF Surveying Services Ltd | Professional & scientific | 2023 |
| LG Brickwork/Drives Ltd | Construction | 2018 |
| LGS Landscaping Ltd | Administrative & support | 2026 |
| Lily Thresher Ltd | Arts & recreation | 2022 |
| Lilyworks Ltd | Construction | 2025 |
| Livingstone Quartz Ltd | Construction | 2026 |
| LJP Associates Limited | Education | 2016 |
| LK Energy Services Ltd | Energy | 2026 |
| Local Carpets Limited | Construction | 2014 |
| London Architectural Hardware Ltd | Wholesale & retail | 2019 |
| London Handles Limited | Wholesale & retail | 2024 |
| London Site Services Limited | Construction | 1994 |
| London Vehicle Contracts Limited | Administrative & support | 2017 |
| Looksharphockley Ltd | Other services | 2024 |
| Lozza's Cleaning Services Ltd | Administrative & support | 2025 |
| Luxury Nails & Spa 31 Ltd | Other services | 2024 |
| M J Kershaw Ltd | Information & communication | 2015 |
| M Morrow Carpentry Services Ltd | Construction | 2013 |
| M&R Management Ltd | Construction | 2023 |
| MAC Commercial Finance Ltd | Financial services | 2024 |
| Magee & Sons Limited | Administrative & support | 2009 |
| Magor Consulting Limited | Administrative & support | 2010 |
| Maidstone Hire Limited | Extraterritorial | 2021 |
| Maizzbala UK Ltd | Hospitality | 2019 |
| Mane K9 Security Services Ltd | Public administration | 2018 |
| Manoly's Takeaway Limited | Hospitality | 2022 |
| Manoly's Thai Limited | Hospitality | 2008 |
| Mark Langleys Digger Hire & Landscape Services Ltd | Construction | 2015 |
| Marko John's Trading Company Limited | Wholesale & retail | 2009 |
| Mars Health Ltd | Health & social care | 2020 |
| Masa Trade International Ltd | Wholesale & retail | 2020 |
| Matco Electrical Limited | | 1985 |
| Matts Enterprises Ltd | Information & communication | 2019 |
| Maurice Investments (Blackpool) Limited | Real estate | 2025 |
| Maurice Investments (Lisbon House) Limited | Real estate | 2025 |
| Maxs Consultants Limited | Construction | 2019 |
| Mayland Capital Ltd | Real estate | 2026 |
| Mayotomi Ltd | Health & social care | 2009 |
| Mecc Essex Limited | Real estate | 2025 |
| Medical & Mobility Warehouse Limited | Arts & recreation | 2021 |
| Medical Legal Secretary Ltd | Health & social care | 2024 |
| MEL and LEO Properties Limited | Real estate | 2026 |
| Mela Glow Cosmetics Ltd | Wholesale & retail | 2025 |
| Melowe Interiors Ltd | Construction | 2016 |
| Merlons Property Management Ltd | Real estate | 2021 |
| Method Kitchens Ltd | Professional & scientific | 2023 |
| MGA Technology Limited | Information & communication | 2014 |
| MHA Cleaning Services Ltd | Administrative & support | 2025 |
| Mike Stapleton & Company Limited | Professional & scientific | 2009 |
| Miller Blake Properties Ltd | Real estate | 2025 |
| Miller Construction Management Ltd | Construction | 2025 |
| Ministry of Horses Limited | Wholesale & retail | 2020 |
| Minnie & ME Hair Studio Ltd | Other services | 2026 |
| MJ Carpentry Hockley Limited | Construction | 2023 |
| MK Property Letting Limited | Hospitality | 2009 |
| MKB Developments Limited | Construction | 2011 |
| Mkjo Property Limited | Real estate | 2025 |
| MKN Contract Services Ltd | Construction | 2019 |
| MLM Property Management Ltd | Real estate | 2020 |
| Momentum Digital Insights Limited | Information & communication | 2017 |
| Mommabears Day Nursery and Preschool Limited | Health & social care | 2017 |
| Mountain View Treherbert Limited | Real estate | 2023 |
| MPH Construction International Ltd | Construction | 2017 |
| MRN General Trading Limited | Wholesale & retail | 2022 |
| Mrpt Academy Limited | Arts & recreation | 2013 |
| MTH Health Ltd | Health & social care | 2018 |
| Mulrooney Mechanical Services Ltd | Construction | 2023 |
| Multi Signmakers Limited | Information & communication | 2015 |
| My Deliveries Ltd | Transport & logistics | 2010 |
| Mystery Sherpa Ltd | Wholesale & retail | 2025 |
| Nashtel Construction Limited | Construction | 2014 |
| National Wildlife Management Ltd | Extraterritorial | 2022 |
| Nell Bevan Properties Ltd | Real estate | 2025 |
| New Space Windows and Conservatories Ltd | Construction | 2016 |
| Next Step Maintenance Ltd | Construction | 2026 |
| Niche Building Ltd | Construction | 2024 |
| Nicholls Cleaners Limited | Real estate | 1972 |
| Nicksted Limited | Professional & scientific | 2026 |
| Nimet Berkay Ltd | Hospitality | 2019 |
| Nissan Figaro Limited | Wholesale & retail | 2021 |
| NM Powell Property Management Limited | Real estate | 2023 |
| Nnhi Ltd | Construction | 2023 |
| NO Bull Architecture Ltd | Professional & scientific | 2018 |
| NO Nonsense Home Improvements Limited | Construction | 2011 |
| NOA Wellbeing Ltd | Health & social care | 2025 |
| Novo Hair Trustee Ltd | Professional & scientific | 2026 |
| NS Keystone Ltd | Real estate | 2025 |
| Nspire Limited | Professional & scientific | 2005 |
| NT Engineering Solutions Limited | Professional & scientific | 2017 |